Deriving individual thoracic parameters of a subject

ABSTRACT

A method of deriving one or more individual thoracic parameters of a subject. The method comprises instructing a subject to perform a thoracic volume manipulation, receiving a plurality of measurements of a plurality of EM signals from a thoracic intrabody area of lungs of the subject during the thoracic volume manipulation, deriving a plurality of thoracic volume values at a plurality of different intervals during the thoracic volume manipulation so that each the thoracic volume value correspond with another of a plurality of estimated thoracic volumes achieved during the thoracic volume manipulation, and calculating at least one individual thoracic parameter of the subject by combining between the plurality of measurements and the plurality of thoracic volume values.

RELATED APPLICATION

This application is claims priority from US provision al patentapplication No. 61/591,915, filed on Jan. 29, 2012.

The content of this document is incorporated by reference as if fullyset forth herein.

FIELD AND BACKGROUND OF THE INVENTION

The present invention, in some embodiments thereof, relates to EM signalanalysis and, more particularly, but not exclusively, to EM signalanalysis devices for monitoring of thoracic biological properties.

Medical instruments in which an echo of a pulse of EM radiation is usedto detect and locate structures in the human body are known, see YOUNG,J. D et. al.

Examination of video pulse radar systems as potential biologicalexploratory tools in LARSEN, L. E., and JACOBI, J. H. (Eds.): ‘Medicalapplications of microwave imaging’ (IEEE Press, New York, 1986), pp.82-105, which is incorporated herein by reference. Such medicalinstruments includes microwave imaging devices, which may be referred toas tissue sensing adaptive radar (TSAR) or imaging and other medicaldevices for detecting and possibly imaging internal biological tissues.The use of electromagnetic waves eliminates the need to expose thetissues to ionizing radiation, as performed during X-ray imaging, and toobtain relatively large tissue contrasts according to their watercontent.

During the last years, various methods and devices have been developedfor diagnosing intrabody tissues of patients using EM radiation. Forexample, International Patent Application Number IL2008/001198, filed onSep. 4, 2008, which is incorporated herein by reference, describes awearable monitoring device for monitoring at least one biologicalparameter of an internal tissue of an ambulatory user. The wearablemonitoring device comprises at least one transducer configured for EMradiation to the internal tissue and intercepting reflections of the EMradiation therefrom in a plurality of continuous or intermittent EMradiation sessions during at least 24 hours, a processing unitconfigured for analyzing respective reflections and identifying a changein the at least one biological parameter accordingly, a reporting unitconfigured for generating a report according to the change, and ahousing for containing the at least one transducer, the reporting unit,and the processing unit, the housing being configured for being disposedon the body of the ambulatory user.

Using EM radar for cardiac biomechanics assessment is mentioned in E. M.Staderini, “UWB radars in medicine,” IEEE Aerospace and ElectronicSystems Magazine, vol. 17, no. 1, pp. 13-18, 2002, which the contentthereof is incorporated herein by reference.

SUMMARY OF THE INVENTION

According to some embodiments of the present invention, there isprovided a device of deriving one or more individual thoracic parametersof a subject. The device comprises a processor, a first interface forreceiving a plurality of measurements of EM signals from a thoracicintrabody area of lungs of a subject, wherein each of the plurality ofmeasurements of EM signals reflects a different time point during athoracic volume manipulation of the subject, a second interface forreceiving a plurality of thoracic volume values, wherein each of theplurality of thoracic volume values reflects a different time pointduring a thoracic volume manipulation of the subject, and an individualthoracic parameter module which uses the processor to calculate at leastone individual thoracic parameter using the plurality of EM measurementsand the plurality of thoracic volume values.

Optionally, the first interface is associated with a probe having atleast one antenna for capturing a plurality of later EM measurementsfrom a subject and a thoracic analysis unit module which monitorsthoracic fluid by an analysis of the plurality of later EM measurementsin combination with the at least one individual thoracic parameter.

Optionally, the second interface is associated with an instrument formeasuring at least one of a breathing airflow of the subject forreceiving the plurality of thoracic volume values.

More optionally, the instrument has a chamber with a single airflowopening to allow the subject to blow therethrough during the thoracicvolume manipulation.

Optionally, the processor is associated with a presentation unit whichpresents instructions indicative of how to perform the thoracic volumemanipulation in a correlated manner with the measurement of theplurality of thoracic volume values.

Optionally, a memory for storing information relating to the at leastone individual thoracic parameter.

Optionally, a processing unit configured to derive one or more clinicalparameters according to the at least one individual thoracic parameterand data relating to electromagnetic (EM) radiation received from aninternal tissue of the subject.

According to some embodiments of the present invention, there isprovided a to method of deriving one or more individual thoracicparameters of a subject. The method comprises receiving a plurality ofEM measurements of a plurality of EM signals from a thoracic intrabodyarea of lungs of a subject performing at least one thoracic volumemanipulation, deriving a plurality of thoracic volume valuescorresponding to a plurality of the plurality of EM measurements, andderiving at least one individual thoracic parameter of the subject usingthe plurality of EM measurements and the plurality of thoracic volumevalues.

Optionally, the deriving a plurality of thoracic volume values comprisesdetermining a breathing value of the subject in a plurality of separateinstances during the thoracic volume manipulation.

Optionally, the plurality of thoracic volume values comprise at leastbreathing value of the subject.

Optionally, the plurality of EM measurements are received from athoracic monitoring device monitoring the lungs; and the methodcomprises calibrating a thoracic analysis device using at least one ofthe at least one individual thoracic parameter.

Optionally, information relating to the at least one individual thoracicparameter is stored during a calibration session of a thoracic analysisdevice and is used for analyzing a plurality of later EM measurementswhich are measured during a monitoring session of the thoracicmonitoring device.

More optionally, the calibrating comprises updating a dielectric modelof a thorax according to the individual thoracic parameters.

More optionally, the dielectric model is modeled with a plurality ofstacked layers having different dielectric properties and selected froma group consisting of skin, fat, muscle, bone, connective tissue andlung.

Optionally, the at least one individual thoracic parameter comprises amember of a group consisting of: heart dimension(s), heart position, fatlayer dimensions, thoracic muscle dimension(s), thoracic ribdimension(s), thoracic rib position, lung volume, lung dimension(s), andthorax dimension(s.

Optionally, the at least one individual thoracic parameter comprisesdielectric related properties of at least one of a thoracic tissue and athoracic organ of the subject.

Optionally, the at least one individual thoracic parameter is used incombination with at least one EM measurement to derive at least oneclinical parameter of the subject.

Optionally, the plurality of EM signals pass through the lungs.

More optionally, the plurality of EM signals are reflected from at leastone object within the thorax of the subject and pass through the lungs.

Optionally, the plurality of EM signals are reflected from the lungs.

Optionally, the plurality of EM signals comprise a plurality of EMsignals having a plurality of different frequencies.

Optionally, further comprising presenting to the subject instructionsindicative of how to perform the thoracic volume manipulation.

More optionally, the method further comprises presenting to the subjectbreathing instructions for the subject to perform during the thoracicvolume manipulation.

Optionally, the thoracic volume manipulation comprises at least oneexhalation and at least one inhalation and performed by the subject.

Optionally, the deriving at least one individual thoracic parameter isperformed according to one or more demographic parameters relating tothe subject.

Optionally, the thoracic volume manipulation is a member of a groupconsisting of a Valsalva maneuver and a Miller maneuver.

Optionally, the thoracic volume manipulation includes performing achange of posture, a change of position, a change of lying angle, achange of posture from sitting to lying, a change of posture from lyingto sitting, and a rising of the legs.

Optionally, the deriving at least one individual thoracic parameter isperformed according to a measured amplitude ratio between a transmittedsignal and a received signal.

More optionally, the at least one clinical parameter comprises one ormore breathing parameters.

More optionally, the one or more breathing parameters include a memberof a group consisting of breathing rate, breathing volumes, tidalvolume, residual volume, functional residual capacity (FRC), total lungvolumes and minute ventilation.

More optionally, the at least one clinical parameter comprises a memberof a to group consisting of fluid and/or gas volume in the thorax and/orlung tissue, percentage of fluid in a lung tissue, parameters indicativeof fluid content and/or content change, and/or percentage of fluidchange in lung tissue.

Optionally, the deriving at least one individual thoracic parametercomprises calculating a phase shift based on the plurality of EMmeasurements.

Optionally, the deriving at least one individual thoracic parametercomprises calculating fluid content of the lungs.

Optionally, the deriving at least one individual thoracic parametercomprises calculating a depth of the lungs.

According to some embodiments of the present invention, there isprovided a method of EM signal analysis. The method comprises receivingat least one individual thoracic parameter of a subject, receiving aplurality of measurements of EM signals from a thoracic intrabody areaof the lungs of the subject, and deriving a clinical parameter of thesubject using the individual thoracic parameter.

Optionally, the at least one individual thoracic parameter comprises aratio between a depth of the lungs and a square root of the volume ofthe lungs.

Optionally, the at least one individual thoracic parameter comprises apopulation average value selected according to at least one demographiccharacteristic of the subject.

Optionally, the analyzing comprises deriving dielectric relatedproperties of the lungs according to the plurality of measurements.

Optionally, the clinical parameter is an indication of lung fluid.

According to some embodiments of the present invention, there isprovided a system for monitoring one or more clinical parameters of asubject. The system comprises an interface for receiving data relatingto electromagnetic (EM) signals received from an internal tissue of asubject, a memory for storing information relating to one or moreindividual thoracic parameters of the subject, the at least oneindividual thoracic parameters being the product of a calculation duringa calibration session using a plurality of EM signal measurements takenwhen the subject undergoes at least one thoracic volume manipulation,and a processing unit configured to derive one or more clinicalparameters according to the data and the information.

Optionally, the system further comprises a receiver for intercepting theEM signals.

Optionally, the processing unit is configured to derive one or moreclinical parameters according to the data and the information during atleast one monitoring session which follows the calibration session.

Optionally, the system comprises a receiver for receiving theelectromagnetic (EM) radiation from an internal tissue of a subject anda communication module configured to provide data relating thereto tothe interface.

Unless otherwise defined, all technical and/or scientific terms usedherein have the same meaning as commonly understood by one of ordinaryskill in the art to which the invention pertains. Although methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of embodiments of the invention, exemplarymethods and/or materials are described below. In case of conflict, thepatent specification, including definitions, will control. In addition,the materials, methods, and examples are illustrative only and are notintended to be necessarily limiting.

Implementation of the method and/or system of embodiments of theinvention can involve performing or completing selected tasks manually,automatically, or a combination thereof. Moreover, according to actualinstrumentation and equipment of embodiments of the method and/or systemof the invention, several selected tasks could be implemented byhardware, by software or by firmware or by a combination thereof usingan operating system.

For example, hardware for performing selected tasks according toembodiments of the invention could be implemented as a chip or acircuit. As software, selected tasks according to embodiments of theinvention could be implemented as a plurality of software instructionsbeing executed by a computer using any suitable operating system.

In an exemplary embodiment of the invention, one or more tasks accordingto exemplary embodiments of method and/or system as described herein areperformed by a data processor, such as a computing platform forexecuting a plurality of instructions.

Optionally, the data processor includes a volatile memory for storinginstructions and/or data and/or a non-volatile storage, for example, amagnetic hard-disk and/or removable media, for storing instructionsand/or data.

Optionally, a network connection is provided as well. A display and/or auser to input device such as a keyboard or mouse are optionally providedas well.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments of the invention are herein described, by way ofexample only, with reference to the accompanying drawings. With specificreference now to the drawings in detail, it is stressed that theparticulars shown are by way of example and for purposes of illustrativediscussion of embodiments of the invention. In this regard, thedescription taken with the drawings makes apparent to those skilled inthe art how embodiments of the invention may be practiced.

In the drawings:

FIG. 1 is a flowchart of a method of deriving individual thoracicparameter(s) of a subject by combining between EM measurements from athoracic intrabody area and correlated thoracic volume values of thesubject's lungs, according to some embodiments of the present invention;

FIG. 2 is a flowchart depicting a process of using a thoracic analysisdevice for monitoring clinical parameters of a subject based on ananalysis of measurements of EM signals from the thorax of a subjectwhere the analysis device is calibrated by using individual thoracicparameters, according to some embodiments of the present invention;

FIG. 3 is a schematic illustration of a system for deriving individualthoracic parameters of a subject, optionally based on the method of FIG.1, according to some embodiments of the present invention;

FIG. 4 is a schematic illustration of a subject who exhales and inhalesin a controlled manner via an instrument for measuring air flow inassociation with the individual thoracic parameter(s) deriving system ofFIG. 3 that concurrently measures measurements of EM signals from thelungs of the subject, according to some embodiments of the presentinvention;

FIG. 5A is a schematic illustration of a multilayer model of the thorax,according to some embodiments of the present invention;

FIG. 5B is a schematic illustration of a multilayer model of the thorax,according to some embodiments of the present invention;

FIG. 6 is a graph depicting amplitude and a phase of an EM measurementsignal captured while a subject performed a Valsalva maneuver, accordingto some to embodiments of the present invention;

FIG. 7 is a closed volume chamber apparatus, according to someembodiments of the present invention; and

FIG. 8 is an experiment graph reflecting a calculation of lung fluidconcentration calculated based on EM measurement of an animal subject,according to some embodiments of the present invention, compared to acomputed tomography (CT) based estimation of the same parameter based onmultiple images acquired along the course of the experiment.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The present invention, in some embodiments thereof, relates to EM signalanalysis and, more particularly, but not exclusively, to derivingindividual thoracic parameters of a subject, calibrating EM signalanalysis devices, and using dielectric thorax models for EM signalanalysis.

According to some embodiments of the present invention there aremethods, devices and systems for calculating individual thoracicparameters of a subject based on an analysis of measurements of EMsignals from the lungs or thorax of the subject and correlated thoracicvolume values of the lungs. The measurements and values are optionallycaptured when the subject undergoes a thoracic volume manipulation. Asused herein, a thoracic volume manipulation may include any procedurethat affects a thoracic volume value of the subject (e.g. a volume ofblood and/or air in the thorax or part thereof) in such manner that thechange in volume value may be controlled and/or calculated and/orestimated, directly or indirectly. Some examples for thoracic volumemanipulation are detailed herein.

According to some embodiments of the present invention, there aremethods and systems of calibrating a thoracic analysis system used formonitoring clinical parameters of a subject, wherein the calibrationincludes using a thoracic monitoring device to detect EM signals from athoracic area of lungs, using an individual thoracic parameter(s)deriving device to extract individual thoracic parameters of thesubject, for example as outlined above and described below, and analysisof measurements of EM signals from the lungs and/or thorax of thesubject may then be performed in a to monitoring session according toindividual thoracic parameters, optionally using a thoracic analysisdevice. The individual thoracic parameters may be recalculated from timeto time, for example periodically, upon initiation, positioning, and/orrelocation of the thoracic monitoring device, and/or the like.

According to some embodiments of the present invention, there aremethods and systems of personalizing a dielectric model of the thoraxaccording to individual thoracic parameters which, are related to thespecific subject. The personalized dielectric model may be used forcalibrating thoracic analysis devices which are used for monitoring oneor more clinical parameters of the subject.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not necessarily limited in itsapplication to the details of construction and the arrangement of thecomponents and/or methods set forth in the following description and/orillustrated in the drawings and/or the Examples. The invention iscapable of other embodiments or of being practiced or carried out invarious ways.

Reference is now made to FIG. 1, which is a flowchart 100 of a method ofderiving one or more individual thoracic parameters of a subject byusing EM measurements from a thoracic intrabody area of the lungs andcorrelated (for example concurrent) thoracic volume values of her lungs,according to some embodiments of the present invention. The one or moreindividual thoracic parameters, which have a direct or indirectmeasurable effect on the propagation of EM signals through the subject'sbody, may be used for personalizing, for example personalizing a modelthat is used for EM signals, and/or calibrating one or more thoracictissue measurements and/or diagnostic devices, for brevity referred toherein as thoracic analysis devices.

The one or more individual thoracic parameters may be or include or bederived from or indicative of or otherwise represent parameters of asubject's thorax that are, or are affected by, one or more of thesubject's heart dimensions, heart position, fat layer size, muscle andrib dimensions, lung volume, lung dimensions, thorax dimensions,thoracic dimensions including antero-posterior depth dimensions, lateralwidth dimensions and/or the like, breathing characteristics, for examplefunctional residual volume of the lung and/or the like. The individualthoracic parameters may include or be to derived from or indicative ofor otherwise represent dielectric related properties of one or more ofthe tissues and/or organs of the thorax of the subject. For example, theindividual thoracic parameters may be or include parameters of adielectric model of the thorax of the subject and/or a model that mapschanges of dielectric related properties of the lungs when physiologicaland/or pathophysiological processes occur, for example the process ofbreathing.

The individual thoracic parameters may be extracted as part of apreliminary session for calibrating the thoracic analysis device, and/ora repetitive process which continuously, randomly and/or iterativelyadapts the thoracic analysis device and/or the like. The method may beimplemented independently to extract individual thoracic parameter(s)without using imaging modalities.

As used herein, EM measurements, also referred to as measurements, maybe measurements of EM radiation and/or signal that is used formonitoring a thoracic tissue parameter, for example fluid level, forexample as described in international patent publication numberWO2009/031149 and/or international patent publication numberWO2009/031150, which are incorporated herein by reference and referredto as the international patent publications. The measurements of EMradiation may be performed in one or more monitoring sessions by anythoracic monitoring device which monitors a thorax and is attachedand/or in proximity to the thorax. The EM measurements may be of EMradiation, such as a single EM beam, induced into the thorax and/orreceived therefrom by the thoracic monitoring device, and is a narrowbandwidth signal, although other acquisition regimes are possible suchas wide bandwidth signals.

As used herein, thoracic volume values may include one or more ofbreathing values such as tidal volume, air volume (e.g. at one or morepoints in time), functional residual capacity, minute ventilation, lungvolumes, thorax and lung dimensions (e.g. at one or more points intime), and breathing rates.

A thoracic analysis system may comprise a thoracic analysis device whichuses measurements of EM signals to monitor and/or assess and/or providesclinical parameters related to the state of pathologic and/or diseaseconditions related to the thoracic tissues and/or organs, for exampleconditions such as heart failure (HF), acute respiratory distresssyndrome (ARDS), acute lung injury (ALI), chronic obstructive topulmonary disease (COPD), pneumonitis, pleural effusion, oncologicdiseases, post-operative edema, pneumothorax, and/or for monitoring thesubject's response to treatment of these or other disease conditions.The system may be used for finding dielectric related propertiesindicating the amount of fluids, such as water, blood, and/orinflammation fluids in the monitored internal tissue and/or organ, forexample, in the pulmonary tissues of the subject. The system may beassociated with, or comprise (e.g. as a single combined device), athoracic monitoring device that receives EM signals from the subject'sthorax, where these signals may be used for said analysis andmonitoring. As used herein, receiving measurement of EM signals orreceiving of EM signals may include receiving data indicative of saidsignals and/or derived from said signals in any form, including forexample a mathematical representation and/or derivation from themeasurements.

As used herein, a dielectric related property of a specific volumedescribes its interaction with EM fields; it is represented by afrequency dependent complex number describing the electricalpermittivity and the conductivity of the volume, as known in the art. Itincludes the magnetic permeability, and/or electric permittivity and/orconductivity of the composite of materials within a specific volume.Such a dielectric related property may be affected by a presence ordistribution of fluid, concentration of substances, such as salts,glucose, in the fluid in the internal tissue and/or organ, the ratio offibrotic tissue, a concentration of inflammatory substance in the fluidin the internal tissue and/or organ and physical configuration of organsor tissues of different properties in the volume measured. Electricproperties, dielectric related properties, and dielectric coefficientsare used interchangeably in this application, all referring to theelectrical and/or magnetic characteristics of a certain volumecontaining none, one or more materials. The dielectric relatedproperties of a material, derived from the intercepted EM radiation,describe its interaction with the EM fields. Different human tissues arecharacterized by different dielectric related properties. The dielectricrelated properties of a pulmonary tissue are affected by the dielectricrelated properties of each of its components. For example, a pulmonarytissue comprises blood, lung parenchyma and air, and its dielectricrelated properties are affected by their relative concentrations. Thedielectric related properties of a tissue are determined predominantlyby its fluid content. For example, a fat tissue, which is of low fluidcontent, is characterized by a relatively to low dielectric coefficient,and a healthy muscle tissue, which is of relatively high fluid content,is characterized by a relatively high dielectric coefficient. Thedielectric related properties of a tissue affect the delivered EMradiation which interacts with the tissue. A change in the dielectricrelated properties of a tissue may be, for example, a change of theattenuation of a delivered EM radiation, a change in the delay caused bythe tissue, a change in the phase modulation of interception, and achange in the dispersion of EM radiation in a tissue.

The thoracic analysis device may be a device used for diagnosing, forexample assessing clinical parameters such as breathing volumes, such astidal volume, residual volume, functional residual capacity total lungvolumes, and minute ventilation. In some embodiments, such parameters,also referred to herein as breathing parameters, may also provideindication of a medical condition, and may help to decide on atreatment, or treatment adjustment, or treatment change, possibly apreventive treatment in order to prevent the development of symptomaticpulmonary edema and/or other severe medical state in a subject. Incertain medical situations, such a preventive treatment may reducemorbidity and mortality rates. The clinical parameters and/or thebreathing parameters may be fluid and/or gas volume in thorax and/orlung tissue values, percentage of fluid in a lung tissue, parametersindicative of fluid content and/or content change, and/or percentage offluid change in lung tissue.

As described above, the method 100 of FIG. 1 may be used forcalibration. The calibration performed according to embodimentsdescribed herein may allow deriving clinical parameters such asvolumetric and/or functional lung parameters in a more accurate manner.Such accurate clinical parameters may be used in the process ofdiagnosis, tissue and/or organ monitoring and/or performance assessmentand/or medical decision aiding procedure. The calibration describedherein reduces effects of specific anatomical, physiological and/orbiological characteristics that may reduce the accuracy of theestimation of these clinical parameters.

For example, reference is made to FIG. 2, showing a flowchart 120depicting a process of using a thoracic analysis device for monitoringclinical parameters of a subject based on an analysis of measurements ofEM signals from the thorax of a subject where the measurements arecalibrated according to individual thoracic parameters or analysisthereof, according to some embodiments of the present invention. Asshown at 121, individual thoracic parameters are derived, for example asdepicted in FIG. 1 and detailed below. Then, as shown at 122 theindividual thoracic parameters or information relating to the individualthoracic parameters (e.g. information indicative of the parametersand/or derived from the individual thoracic parameters), may be storedas calibration data for later use, for example as parameters of adielectric model.

Optionally, clinical parameters are also derived using the same EMmeasurements, as shown in 126. Optionally a single device is used toderive individual thoracic parameters and to use them to derive clinicalparameters using the same and/or later EM signals.

Now, as shown at 123, operational EM measurements are analyzed using thecalibration data to extract clinical parameters, for example, at one ormore later measurement sessions. As shown at 124 and 125 whenever a newmeasurement is done and the calibration is found to be not up to date,for example as it was not acquired for a long time, acquired after morethan a certain period in which the thoracic analysis device was usedand/or the like, the process depicted in 121-123 is repeated.

Reference is also made to FIG. 3, which is a schematic illustration of adevice 200 for deriving individual thoracic parameters of a subject,optionally based on the method of FIG. 1, according to some embodimentsof the present invention. The individual thoracic parameter(s) derivingdevice 200 may be a component of an analysis system for monitoringthoracic fluid or a separate calibration device. The individual thoracicparameter(s) deriving device 200 optionally includes a processor 201,for example a microprocessor, an EM signals interface 202 which receivesmeasurements of EM signals from one or more EM probes 205 that isdirected to capture EM signals from a thoracic intrabody area of lungsof a subject. The one or more EM probes 205 may be included with theprocessor 201 in a single device or be otherwise associated one with theother so as to provide the EM signals interface 202 with measurements ofEM signals taken from the one or more EM probes 205. The probe 205includes one or more transducers each with one or more antenna(s). Oneor more transducer(s) may be used for transmitting an EM signal beamwhile other transducer(s) may be used for intercepting the EM signalbeam, or the same transducer may be used for capturing the reflected EMsignal beam. The EM signals interface 202 may communicate with thetransducer(s) via a subject management unit, for example as described inthe to International Patent Application Number IL2011/000377 filed onMay 12, 2011. For example, the EM signal beam passes through lungs, forexample from one side to another and/or reflected from an internalobject in the body, such as the heart.

As further described below, for deriving of individual thoracicparameters, the EM measurements may be taken at different states of thelungs where in each state the lungs have a different thoracic volume.The different thoracic volumes may be achieved during a thoracic volumemanipulation undergone by the subject. The individual thoracicparameter(s) deriving device 200 further includes a thoracic volumevalue interface 203.

The thoracic volume value interface 203 may receive thoracic volumevalues from one or more volume probe(s) 206, for example as describedbelow. In such embodiments, thoracic volume value(s) and ameasurement(s) of EM signals taken during a common thoracic volumemanipulation may be correlated.

Optionally, the individual thoracic parameter(s) deriving device 200includes an individual thoracic parameter module 204 which uses theprocessor 201 to derive one or more individual thoracic parameters usingthe EM signal measurements and correlated thoracic volume values.

In use, as shown at 101 of FIG. 1, measurements of EM signals from athoracic intrabody area of lungs of the subject are received. Themeasurements are taken at a set of different thoracic volumes, which areoptionally achieved during a thoracic volume manipulation undergone bythe subject, for example as described below. The subject may beinstructed to perform the thoracic volume manipulation, or the thoracicvolume manipulation may be applied to the subject, in correlation withthe operation of the individual thoracic parameter(s) deriving device200.

Optionally, the subject may perform the thoracic volume manipulationwhile operation of the individual thoracic parameter(s) deriving device200 is operated in correlation with the subject's performance ofmanipulation.

Optionally, individual thoracic parameter(s) deriving device 200operates irrespective of the performance of the thoracic volumemanipulation, but data and/or information are analyzed in correlationwith the performance of the thoracic volume manipulation.

In addition, as shown at 102 of FIG. 1, thoracic volume values, forexample thoracic fluid and/or air volume values, are received. Thethoracic volume values are to taken during the set of different thoracicvolumes which are optionally achieved during the thoracic volumemanipulation.

Optionally, the subject is instructed to perform said thoracic volumemanipulation in a correlated manner with the deriving of the thoracicvolume values. For example, instructions may be presented, for exampleaudibly played and/or visually displayed correlatively with the outputsof the volume probe(s).

Now, as shown at 103, EM measurements and thoracic volume values areused to calculate one or more individual thoracic parameters at each oneof the different thoracic volumes by combining between respectivecorrelated EM measurements and thoracic volume values.

During the interception of EM signals, the depth of the lung (D) or thethickness of some of the layers may change, for instance as an outcomeof a thoracic volume manipulation, for example the subject's breathing.

Optionally, in order to calibrate a thoracic analysis device, forexample to reduce or limit the effect of bodily movements of the chestduring the measurement of the EM measurements, for example movementsassociated with the breathing process and/or other movements, movementsare measured and modeled. For example, an electromechanical device in aform of a strap may be placed around the chest of the subject to providereal-time continuous measurements of thoracic volume values, for examplethe subject's chest circumference, and or in other forms to provide ameasurement of the depth of the thorax (front to back), while s/he ismeasured by the thoracic monitoring device the measurements of EMsignals taken by which may be used to monitor thoracic fluid. Thesemeasurements may be used to provide corrections to a dielectric lungmodel. For example, D may be corrected in each measurement bymultiplying the change in circumference by a factor.

Additionally or alternatively, the subject may be instructed to performabdominal breathing to minimize the movement of the rib cage and theexpansion of the lung during breathing as a result of the downwardexpansion of the lungs in such breathing replacing much of the sidewardexpansion associated with regular breathing. Such breathing may beencouraged by providing the subject with feedback, for example by usingthe abovementioned electromechanical circumference measurement device,indicating when minimal changes of the chest circumference are detected.Another such to option would be to use the circumference measurementdevice, or tiltmeter devices or accelerometer devices or other suchdevices in order to follow the movement of the rib cage and selectperiods of time during which minimal movement are detected.

In order to measure thoracic volume values during a set of differentthoracic volumes, the subject is instructed to perform or is subjectedto a thoracic volume manipulation, for example by breathing in a certainmanner. For example the subject may be instructed to breathe normallyfor a given time, then in an extreme manner (e.g. deep exhalations andinhalations) for another period of time. These instructions may beimplemented using a graphical user interface (GUI) providing a real-timefeedback, targets and corrections to the subject in order to achieve agiven breathing pattern and/or a characteristic. In another example, thesubject is required to inhale or exhale a predefined air volume duringthe monitoring of the lung, for example while EM signal is received fromher lungs. This process may be implemented using an apparatus thatmeasures and/or controls the amount of air that is inhaled and/orexhaled. For example, an air flow meter which measures the amount ofinhaled and/or exhaled air, for instance a pneumotach or a spirometer,is used for instructing the subject and identifying thoracic volumevalues taken during a set of known thoracic volumes. In another example,a bag, a balloon and/or an air container may be used for controlling theinhaling and/or exhaling volume of the subject, where the bag, theballoon and/or the air container has a known capacity and the subject isrequired to exhale into the balloon until the balloon inflates into apredefined capacity, or where the subject is required to inhale from theballoon until the balloon deflates from its predefined capacity. Inanother example, a piston like air chamber may be used for measuringand/or controlling air volume inhaled and/or exhaled by the subject,where optionally an indicator on the chamber indicates the volume of airinhaled and/or exhaled. In yet another example, the thoracic volumemanipulation includes control and/or measurement of the volume of air ina subject's lungs using an artificial respiration device, for example aventilator, (for example when the subject is anesthetized, comatose orotherwise incapacitated).

In another example, thoracic volume values are taken during the set ofdifferent thoracic volumes which are achieved using an air supplyapparatus which supplies air for inhalation, and collects exhaled air ina controlled and or measured quantity. In some embodiments, a mechanicalventilator may be used. Optionally, the air supply apparatus isconnected to a monitoring apparatus and measures airflow concurrentlywith the measurements of EM signals from the lungs of a subject foridentifying individual thoracic parameters, optionally for thecalibration of the monitoring apparatus.

For example, FIG. 4 depicts a subject 301 who exhales and inhales in acontrolled manner via an instrument for measuring air flow 302, such asa spirometer, while the individual thoracic parameter(s) deriving device200 concurrently measures EM signals from the lungs using one or moreprobes 304. The instrument for measuring air flow 302 may be supportedby air from a pump, for example via a pump tube 305.

The measurements from the instrument for measuring air flow 302 areforwarded to the individual thoracic parameter(s) deriving device 200for processing as described herein, for example via a data link 303.

Such controlled or measured changes of air volumes, are indicative ofindividual thoracic parameters, namely dielectric related properties ofthe lungs, optionally in a manner that is described in a dielectricthorax model, for example as described below. This allows calibratingthe model based measurements.

According to some embodiments of the present invention, metadata isreceived and used for adjusting the calculated individual thoracicparameters. The metadata may include user generated metadata such asdemographic parameters describing the subject, for example age, gender,height, weight, and/or anatomical dimensions. The metadata may includeand/or be derived using data measured by mechanical measuring devices,inferred from radiographic images and/or extracted using other means.Using this information the apparatus the individual thoracic parametersmay be calculated more accurately.

In some embodiments of the present invention, the individual thoracicparameter(s) deriving device 200 uses one or more body attached sensorsto obtain EM measurements while measurements of air quantities, whichare inhaled and exhaled by the subject, are provided to the individualthoracic parameter(s) deriving device 200 via a flow meter.

Optionally, a model describing the dielectric properties of the lung atdifferent thoracic volume values is used to generate a set of equationsto derive the one or more individual thoracic parameters. In such anembodiment, such a model optionally represents a relationship betweendynamic lung content parameters, such as lung air and to lung fluid,such as blood, and the individual thoracic parameters optionally indifferent thoracic volumes.

Optionally, the dielectric model may describe the dielectric relatedproperty of the lung as a function of dielectric related properties ofair, lung fluids, and lung tissues, and their respective volumes,composition, and/or concentration. For example, the lung of a normalperson is composed of approximately 0.5 liter (L) to 0.8 L of blood,approximately 0.5 L of lung tissue, and approximately 1.5-5 L of air,depending on the amount or air inhaled and exhaled in the process ofbreathing. The overall lung dielectric coefficient may be estimated tobe the average of the dielectric coefficients of the three components ofair, blood and tissue according to their respective volume andconcentration. Another option is to estimate the equivalent dielectriccoefficient by averaging a square root of the dielectric coefficientsaccording to a respective volume concentration, and calculating a squareof the total. Other dielectric models for estimating the equivalentdielectric coefficient of a mixture exist. Such methods may be used tomodel the lung and/or other thoracic tissues and/or organs' dielectricproperties at different periods along the breathing cycle and fordifferent edema states or other lung changes. For example, at the end ofinspiration a model can assume 2 liters of air present in the lungs, and1.5 liters of air content at the end of expiration.

Reference is now made to a calculation that is based on a dielectricthorax model that assumes an anatomical configuration where a collectionof tissues including the lung that makes up a medium traversed by the EMsignals. For example, the dielectric thorax model is defined as a chestwall model as described in international patent application numberWO2009/031150 filed on Sep. 4, 2008.

Reference is now made to Equations 1-7, which are a mathematicaldescription of an exemplary dielectric thorax model and a process ofacquiring individual thoracic parameters which are substituted in thedielectric thorax model for calibration.

Optionally, the model is based on the following assumption:

$\begin{matrix}{{E_{ratio} = \frac{E_{r}}{E_{t}}}{where}{\frac{E_{r}}{E_{t}} = {f\begin{pmatrix}{V,V_{fluid},V_{air},{{Dielectric}\mspace{14mu} {properties}\mspace{14mu} {of}\mspace{14mu} {the}}} \\{{{thoracic}{\mspace{14mu} \;}{tissues}},{{Anatomical}\mspace{14mu} {parameters}}}\end{pmatrix}}}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

where V denotes a total lung tissue volume composed of gas (i.e. air)and lung fluid, v_(fluid) denotes a total volume of fluids in the lung,for example measured in cubic centimeter (CC), where the fluid contentcomprises a combination of extravascular, intravascular, andintracellular fluid, and V_(air) denotes lung air content in volumeunits.

$E_{ratio} = \frac{E_{r}}{E_{t}}$

denotes a ratio between a received (i.e. intercepted; E_(r)) signal anda transmitted (i.e. induced; E_(t)) signal in terms of the electricalcomponent of the EM field.

It should be noted that lung fluid includes tissue contents and fluidsincluding blood.

It should be noted that some embodiments of the present invention arenot limited to one model or another and may use various models thatdescribe fluid content of the lung as part of its parameters.

Optionally, the dielectric thorax model is modeled as stacked layers,such as skin, fat, muscle, and lung, where each layer has a differentdielectric property, for example as depicted in FIG. 5A. Optionally thereference chest wall model maps expected dielectric coefficients oftissues of an exemplary reference model of EM properties of tissues of athorax section. For example, the model at FIG. 5A includes the followinglayers with the following possible thicknesses: a skin tissue layer (1-3mm), a fat tissue layer (50-500 mm), a muscle tissue layer (50-200 mm),a bone layer (30-60 mm), and a pulmonary tissue layer (˜100 mm). Anotherexample is depicted at FIG. 5B which is a side to side model thatincludes the following layers with the following possible thicknesses: askin tissue layer (1-3 mm), a fat tissue layer (1-5 cm), a muscle tissuelayer (1-2 cm), a bone layer (0.5 cm), a pulmonary tissue layer (˜100mm), a bone layer (0.5 cm) a muscle tissue layer (1-2 cm), a fat tissuelayer (1-5 cm), and a skin tissue layer (1-3 mm).

For some or all the layers, the reference chest wall model includes oneor more of the following parameters: a relative dielectric coefficient,thickness, for example as described above, an estimated signal shape,and an equivalent frequency response of a layer capturing an effectimposed on an EM signal propagating therethrough, for example anestimation of attenuation and dispersion of a pulse which propagatesthrough the respective layer. Such a model may be presented in phasornotation as:

$\begin{matrix}{\overset{\_}{E_{ratio}} = ^{{- j}\; 2\pi {\frac{f}{c} \cdot {\sum_{i \in {tissues}}{D_{i} \cdot \sqrt{ɛ_{i} + {{j \cdot ɛ^{\prime}}i}}}}}}} & {{Equation}\mspace{14mu} 2}\end{matrix}$

where E_(ratio) denotes a measured phasor relationship between atransmitted signal and a received signal representing the electricalcomponents of the electromagnetic radiation at a given frequency, D_(i)denotes a propagation distance within i^(th) layer (layer thickness) forexample skin layer or fat layer, ∈_(i) and ∈′_(i) denote real andimaginary parts of dielectric permittivity (dielectric coefficient) ofthe i^(th) layer, f denotes a frequency for which the phase shift iscalculated, π denotes a Pi constant, and C denotes a speed of light invacuum constant.

Analysis may now be based on φ=Phase( E_(ratio) ) and/or Amp=| E_(ratio)|.

In some embodiments a dielectric thorax model describing a certain phasemay be analyzed as follows:

$\begin{matrix}{\phi = {\sum\limits_{i \in {tissues}}{2{\pi \cdot D_{i} \cdot \sqrt{ɛ_{i}} \cdot \frac{f}{c}}}}} & {{Equation}\mspace{14mu} 3}\end{matrix}$

where √{square root over (∈_(i))}≈Re√{square root over (∈_(i)+j·∈′_(i))}when the region of interest (ROI) is the lungs, a certain phase may beanalyzed as followed:

$\begin{matrix}{\phi = {\hat{\phi} + {2{\pi \cdot D_{lung} \cdot \sqrt{ɛ_{lung}} \cdot \frac{f}{c}}}}} & {{Equation}\mspace{14mu} 4}\end{matrix}$

where {circumflex over (φ)} denotes a phase shift is an outcome of alllayers other than the lung layer, including phase shift incurred by theone or more EM probes 205 and D_(lung) denotes a length of the lung,defined as the length of the region of lung tissue measured by theapparatus using EM fields, and it is assumed, in this model, a lungdielectric constant per subject in a repeated similar body posture withsimilar positioning of the one or more EM probes 205, for exampletransducers.

In some embodiments of the present invention, the lung dielectricconstant is determined by a linear material mixture model, for example amaterial mixture model defined as follows:

$\begin{matrix}{ɛ_{lung} = \frac{{V_{air} \cdot ɛ_{air}} + {V_{fluid} \cdot ɛ_{fluid}}}{V}} & {{Equation}\mspace{14mu} 5}\end{matrix}$

where when ∈_(air)=1 and ∈_(fluid)≈50, V_(air)·∈_(air) is negligiblewhen compared with V_(fluid)*∈_(fluid). If a frequency of f=3 GHz isselected then Equation 4 equals to:

$\begin{matrix}{{\phi \cong {\hat{\phi} + {450 \cdot D_{lung} \cdot \sqrt{\frac{V_{fluid}}{V}}}}}{{where}\mspace{14mu} \sqrt{\frac{V_{fluid}}{V}}}} & {{Equation}\mspace{14mu} 6}\end{matrix}$

may be referred to as a root fluid concentration (RFC) so that Equation6 is evident that changes in φ, assuming other model parameters arerelatively constant, are linearly correlated with changes in RFC whichis an indication of lung fluid changes.

In some embodiments, the use of controlled and/or measured changes inair content enables extraction of other lung fluid indications. Asdescribed above, each of a set of thoracic volume values is measuredduring another of a set of different thoracic volumes which are achievedin a controllable manner.

In some embodiments of the present invention, controlled and/or measuredchanges in air content enables extraction of individual thoracicparameters. For example, if EM measurements are taken with knownquantities of inhaled air with respect to, for example, a deflatedvolume, for example end of expiration volume, also known as a functionalresidual capacity (FRC) state of the lung, then using the notation of

$\begin{matrix}{\phi_{i} \cong {\hat{\phi} + {450 \cdot D_{lung} \cdot \sqrt{\frac{V_{fluid}}{V_{deflated} + {\Delta \; {Vi}}}}}}} & {{Equation}\mspace{14mu} 7}\end{matrix}$

which is a six variables equation, that may be solved to obtainparameters {circumflex over (φ)}, V_(deflated), and the termD_(lung)·√{square root over (V_(fluid))}, where V_(deflated) denotes atotal lung capacity at the end of expiration by substituting knownvalues of inhaled quantities, for example three or more, for instanceΔV₁, ΔV₂ and ΔV₃ and corresponding phase measurements, for instance φ₁,φ₂ and φ₃.

Optionally, in use, the subject is instructed to perform, for examplesequentially, a combination of breathing patterns, for example forcedexhale pattern, maximal inhale pattern, and normal breathing patternsand the estimated breathing values are used to infer values for ΔV₁, ΔV₂and ΔV₃.

Obtaining a measurement or estimation of D_(lung) allows calculatingV_(fluid). Some examples of how to obtain D_(lung) are herein provided.It should be noted that the acquired individual thoracic parameters maybe used for calibration. In such embodiments, the extracted V_(deflated)(i.e. FRC) and V_(fluid) are two individual thoracic parameters whichallow deducing another individual thoracic parameter, fluidconcentration (FC). For example, FC is calculated as follows:

$\begin{matrix}{{FC} = \frac{V_{fluid}}{V_{deflated}}} & {{Equation}\mspace{14mu} 8}\end{matrix}$

Optionally, the individual thoracic parameters are used for adjusting ananalysis of EM measurements obtained while monitoring of intrabodythoracic tissues.

Reference is now made to Equations 9-19, which are a mathematicaldescription of an exemplary dielectric thorax model, a nonlinear mixturemodel, and a process of acquiring individual thoracic parameters whichare substituted in the nonlinear mixture model for calibration. In theseembodiments the individual thoracic parameters are dielectric lungconstants. Optionally, a nonlinear material mixture model is defined asfollows:

$\begin{matrix}{\sqrt{ɛ_{lung}} = \frac{{V_{air} \cdot \sqrt{ɛ_{air}}} + {V_{fluid} \cdot \sqrt{ɛ_{fluid}}}}{V}} & {{Equation}\mspace{14mu} 9}\end{matrix}$

-   -   where if ∈_(air)=1 and ∈_(fluid)≈50, and f=3 GHz then Equation        becomes:

$\begin{matrix}{\phi \cong {\hat{\phi} + {63 \cdot D_{lung} \cdot {\frac{V_{air} + {V_{fluid} \cdot \sqrt{50}}}{V}.}}}} & {{Equation}\mspace{14mu} 10}\end{matrix}$

In some embodiments of the present invention, controlled and/or measuredchanges in air content enables extraction of individual thoracicparameters. For example, if EM measurements are taken with knownquantities of inhaled air with respect to, for example, a deflatedvolume, for example end of expiration volume, also known as a FRC stateof the lung, then using the notation of:

$\begin{matrix}{\phi_{i} \cong {\hat{\phi} + {63 \cdot D_{lung} \cdot \frac{V_{{air},{deflateed}} + {\Delta \; {Vi}} + {V_{fluid} \cdot \sqrt{50}}}{V_{deflated} + {\Delta \; {Vi}}}}}} & {{Equation}\mspace{14mu} 11}\end{matrix}$

where V_(deflated)=V_(air,deflated)+V_(fluid) which denotes a total lungcapacity at to the end of expiration.

In this example, values of inhaled quantities, for example three, forinstance ΔV₁, ΔV₂ and ΔV₃ and corresponding phase measurements φ₁, φ₂and φ₃ may be used to solve and obtain the parameters {circumflex over(φ)},V_(deflated) and the term D_(lung)·V_(fluid). Similarly to theabove, fluid concentration (FC) may be calculated as follows:

$\begin{matrix}{{FC} = \frac{V_{fluid}}{V_{deflated}}} & {{Equation}\mspace{14mu} 12}\end{matrix}$

According to some embodiments of the present invention, relativeparameters are extracted; for example, a lung fluid change. The relativemeasurement may be calculated as follows (taking into account equations4 and 5):

$\begin{matrix}{\phi = {\hat{\phi} + {2\pi \; {{f/c} \cdot D_{lung} \cdot \sqrt{\frac{{V_{air} \cdot ɛ_{air}} + {V_{fluid} \cdot ɛ_{fluid}}}{V}}}}}} & {{Equation}\mspace{14mu} 13}\end{matrix}$

where controlled and/or measured changes in air content with respect to,for example, a deflated volume state of the lung may be calculated asfollows:

$\begin{matrix}{\phi = {\hat{\phi} + {2\pi \; {{f/c} \cdot D_{lung} \cdot \sqrt{\frac{{\left( {V_{{air},{deflated}} + {\Delta \; V}} \right) \cdot ɛ_{air}} + {V_{fluid} \cdot ɛ_{fluid}}}{V_{deflated} + {\Delta \; V}}}}}}} & {{Equation}\mspace{14mu} 14}\end{matrix}$

Using a measured or controlled change in V_(air) (i.e. ΔV) and assumingit is small enough, and using a linear approximation, Δφ=Const·(ΔV)where Const may be calculated using a calibration process. Thus,according to the above assumptions, and seeing from the Equations abovethat ΔV may be substituted by (ΔV_(fluid)·∈_(fluid)), changes in lungfluid content (i.e. ΔV_(fluid)) may be estimated as follows:ΔV_(fluid)=Δφ/(Const·∈_(fluid)).

As described above, the thoracic volume values are taken during the setof different thoracic volumes which are optionally achieved during athoracic volume manipulation.

According to some embodiments of the present invention, the subject isinstructed to perform a Valsalva maneuver and/or Miller maneuver (alsoknown as Muller's maneuver) while electromagnetic waves are measured,optionally using a closed volume chamber apparatus. The subject may, forexample, be instructed to exhale normally and from the end of theexpiration or the end of inspiration state to perform a Valsalva and/orMiller maneuver. The Valsalva maneuver is performed when the subjectexhale against a closed airway, usually when closing his mouth andpinching his nose. The Miller maneuver is performed when the subjectinhales against a closed airway, usually closes his mouth and pincheshis nose, optionally at the end of expiration. Optionally, the subjectis instructed to perform the maneuver for a timed duration. Thesemaneuvers affect pressure in the airways of the lung, and accordinglyaffect the blood and blood volume in the lungs. Since in the ValsavaManeuver for example a specific blood volume is removed from the lungregion due to increased pressure over a time period, this maneuverinduces a controlled change in the dielectric properties of the lung.Given a specific pressure that is maintained for a long enough periodthe lungs reaches an equilibrium in which a specific amount of blood isremoved from. For example, when a 40 Millimeter-Quecksilbersäule (mmHg)pressure is applied for 10 second (sec) or more, 200 cc of blood isremoved from the lungs and when a 50 mmHg pressure is applied for 10 secor more, 250 cc of blood is removed. Several pressure levels andcorresponding blood fluid removed volumes may be created, see alsoDougal Mcclean et al. titled: “Noninvasive Calibration of CardiacPressure Transducers in Subjects With Heart Failure: An Aid toImplantable Hemodynamic Monitoring and Therapeutic Guidance”, Journal ofCardiac Failure Vol. 12 No. 7 2006.

In this example case, the Valsalva and/or Miller maneuver changes theamount of fluid in the lungs and thus Equation 6 may be set as follows:

$\begin{matrix}{\phi \cong {\hat{\phi} + {450 \cdot D_{lung} \cdot \sqrt{\frac{V_{fluid} + {\Delta \; V\; F_{i}}}{V_{deflated}}}}}} & {{Equation}\mspace{14mu} 15}\end{matrix}$

where ΔVF denotes an amount of blood fluid removed and/or added by themaneuver. As described above, different parameters for a number ofequations may be generated by instructing the subject to perform severalmaneuvers. Similar to the above, three such equations allow deducing thefollowing individual thoracic parameters: {circumflex over(φ)},V_(fluid), and a term D_(lung)/√{square root over (V_(deflated))}.Obtaining D_(lung) allows calculating V_(deflated). This method may becombined with other methods for creating controlled and/or measuredchanges in the characteristics of the thorax or the lung and thecorresponding model parameters.

Optionally, the subject is instructed to perform a Miller and/orValsalva maneuver while electromagnetic waves are measured, optionallyusing a closed volume chamber apparatus.

The Miller maneuver involves forcible inhalation against a closedairway. It may be performed in a similar manner to a Valsalva maneuverwith similar results (increasing the amount of blood fluid in thelungs). It may be performed with or without a duration definitions, withor without additional pressure measurement of the intensity and/orcontrol of the negative air pressure; and may be controlled using asimilar closed volume chamber apparatus.

Other maneuvers may also be used to change the amount of fluid in thelung in a controlled manner. For example, a change of posture, change ofposition, a change of lying angle, a change of posture from sitting tolying or vice versa, a raising of the legs in a lying position and/orthe like. These maneuvers may be controlled and/or measured to improveaccuracy, for example the posture or posture change may be measured andtimed, for example using tilt meters, accelerometers, gyroscopes and/orthe like. For example, the angle of the torso and/or the angle of thelegs may be measured or controlled during the maneuver. Also theduration of the maneuver or its parts may be measured. Also peripheraleffects, for example blood pressure, heart rate, respiration rate, maybe measured before during or after the maneuver to help in theassessment of the extent of the maneuver and the expected change in thefluid content of the lungs. As with the Valsalva maneuver, a givenmaneuver creates a new equilibrium state that removes or adds a givenamount of fluid to the thorax.

The change, measured in the intercepted EM signal, during the controlledchange induced in the subject, may be analyzed, using a dielectricthorax model, to estimate the individual thoracic parameters for thedielectric thorax model. For example, as described above, the individualthoracic parameters may be used to in order to calibrate thoracicanalysis device. Therefore, by inducing a controlled change of the todielectric related properties of a monitored lung, for example, whileperforming EM measurements of the lung, it is possible to track thechanges in the received EM signal in view of the induced change. Thismethod may be used to calculate parameters of the model for the subjectbeing monitored using the EM measurements.

These controlled changes may be induced once, several times,periodically, and/or continuously throughout an EM measurement sessionand/or a monitoring period, in one or more manners, and using one ormore degrees of intensity. These controlled changes may include the useof the above methods, and/or other techniques for changing thedielectric related properties of the measured tissue, as mentionedabove.

Optionally, the EM signal is measured while the subject performs theabove maneuvers. For example, FIG. 6 depicts phase 171 and amplitude 172of an EM measurement signal captured while the subject performed aValsalva maneuver and analyzed over a period of a few minutes andmodulated by the breathing of the subject. Three periods where theValsalva maneuver is performed and a respective removal of a specificvolume of blood from the subject's lung are seen at 173-175. EMmeasurements may be taken during one or more of the maneuvers and/or ata time when the maneuver is not performed.

According to some embodiments of the present invention, the thoracicvolume values are taken during the set of different thoracic volumeswhich are acquired using a closed volume chamber apparatus, for examplethe volume chamber apparatus 161 depicted in FIG. 7. The closed volumechamber apparatus 161 indicates air pressure in the lung of the subjectover a measured amount of time.

Optionally, the subject is instructed to inhale or to exhale against theclosed chamber 162 through a single airflow opening, for example amouthpiece 163, while the apparatus 161 induces and/or measures airpressure in the chamber 162 using an air pump 165 and/or a pressuresensor 164. The pump 165 and the pressure sensor may be connected withdata links 167/8 to an individual thoracic parameter(s) deriving device200. The apparatus 161 may be controlled by a processing unit that maybe embedded in the closed volume chamber apparatus 161. The processingunit may record the pressure measurements, and/or measure the durationthat the pressure is maintained and/or control the air pump to createthe desired pressure in the chamber. The to processing unit maycommunicate with a subject interface unit to provide information to beused as a basis for instructing the subject to achieve the desiredbehavior (inhaling or exhaling against the closed chamber to create thedesired pressure) for the desired duration.

In use, apparatus 161 may be used to extract the thoracic volume valuesduring a set of identified thoracic volumes.

According to some embodiments of the present invention, the individualthoracic parameters include estimated physiological parameters of thesubject. For example, the ratio between the lung's depth (e.g.anteroposterior dimension of the lung) and the square root of the lungvolume may also be assumed based on the general population, and/oradjusted based on subject specific characteristics for example weight,height, chest, circumference, and the like.

In another example, tidal volume is assumed to be an average volume, forinstance for an adult 500 cubic centimeter (cc) and/or adjusted based onthe weight of the subject, for instance assuming a value for a normalindividual at rest of 7 milliliter (mL) per kilogram (kg) of body weightand/or in correlation with BMI or fitness level and/or any other subjectspecific characteristic. The tidal volume may be estimated based onaverage minute ventilation (defined as the tidal volume multiplied bythe respiration rate given as breaths per minute) of, for example, 6liters per minute and adjusted based on a measured respiration rate, see“Tintalli's Emergency Medicine, Ch. 22”; Todd L. Slesinger, M.D.; 2011.Similarly, respiratory functional residual volume may be estimated asthe general population overage of 2500 cc and/or based on weight and ageof the subject, for instance(0.0275*Age[years]+0.0189*Height[cm]−2.6139) liters for normal-weightindividuals and (0.0277*Age[years]+0.0138*Height[cm]−2.3967) liters foroverweight individuals, see MILLER, WAYNE C.; SWENSEN, THOMAS; WALLACE,JANET P. (February 1998). “Derivation of prediction equations for RV inoverweight men and women”, Medicine & Science in Sports & Exercise 30(2): 322-327.

According to some embodiments of the present invention, the clinicalparameters include breathing parameters such as a breathing rate, minuteventilation, a tidal volume, a residual volume, and/or FRC.

Optionally, the breathing values, used as thoracic volume values, forexample to the tidal volume, are used for calibrating using an EM probethat captures EM signals from the lungs. Following calibration the EMmeasurements may be used to continue and provide the tidal volumemeasurements; and in addition minute ventilation may be provided byusing the tidal volume measurement multiplied by a breathing rate value.

The breathing rate value may be assessed using one or more frequencyanalysis methods applied to the measured EM signal. For example, lookingfor a maximum power peak in the frequency domain, a representation ofthe phase of the measured EM signal in a range between 2/60 Hertz (Hz)and 1 Hz, after employing methods for removing the effects heart beatingfrom the signal.

Optionally, residual volume (RV) may be calculated using the abovemethod while the subject exhales as much as she can. In this case, theresulting equation

$\phi_{i} \cong {\phi + {450 \cdot D_{lung} \cdot \sqrt{\frac{V_{fluid}}{V_{R\; V} + {\Delta \; {Vi}}}}}}$

may be used with controlled and/or measured changes in air content toobtain RV.

Breathing parameters are of importance in relation to severalpathologies and medical conditions, for example heart failure, chronicobstructive pulmonary disease (COPD), interstitial lung disease (ILD),and/or acute lung injury (ALI).

Optionally, a noise model is generated and used to improve thecalculation of the individual thoracic parameters, for example using aleast square error method.

According to some embodiments of the present invention, a thoracicanalysis device is calibrated based on individual thoracic parameter(s)which are calculated independently from information about currentthoracic volumes. For example, the individual thoracic parameter(s) mayinclude a lung diameter that is approximated according to the average inthe population estimated at about 17.1 centimeters (cm) or any otherappropriate estimated average. This and other approximations may be moreaccurate if they are estimated based on the subject's general physicalparameters, such as height, weight, body mass index (BMI), age, genderand/or fat-muscle ratio. Another option is to approximate lung diameteraccording to a chest perimeter of the subject.

The chest perimeter may be measured under the armpits of the subject andmultiplied by a factor such as 0.164 (or any other appropriate factor).

Optionally, lung diameter is approximated according to chest depth ofthe subject.

Optionally, the chest (i.e. depth front to back) may be measured using ato designated mechanical tool. The measuring is optionally correlatedwith phase shift measuring and optionally multiplied by a factor.

Another example of independently calculated individual thoracicparameter(s) are individual thoracic parameters measured using animaging modality, such as computerized tomography (CT), magneticresonance imaging (MRI), ultrasound imaging, and/or radiographic, and/orother imaging methods or any other known system for finding the lungwidth along the measurement path. For example, dielectric relatedproperties of the tissues in the thorax, and specifically in regions ofinterest may be estimated.

For example, fluid to air ratio of the lung tissue, fat tissue and/orother tissues may be estimated based on the analysis of image graylevels in regions of interest in a CT image, or other imagingmodalities. Such an analysis of a CT image to assess lung fluidconcentration may be performed by extracting a three dimensional (3D)region of interest in the image, say within the lung, or the entire lungregion; and computing the average attenuation level of the region inHounsfield units (HU). HU, may be converted into fluid concentration(i.e. the ratio of the volume of blood, parenchyma and any pathologicalfluid to the total volume) using a linear scale. Transformation from HUto fluid concentration percentage may be performed by assigning a valuebetween 0% and 100% along the range of HU values, between 1000 HU (thecalibrated radiodensity of air) and 0 HU (the calibrated radiodensity ofwater), for instance 800 HU is equivalent to 80% air content and 20%fluid concentration.

Another example of independently calculated individual thoracicparameter(s) are individual thoracic parameters measured using EM signalreflected from the thorax, for example the measuring of D as describedin Staderini EM, UWB radars in medicine, IEEE Aerospace and ElectronicSystems, Volume: 17 (1) 2002.

According to some embodiments of the present invention, breathing valuesare quantified by processing amplitude of an intercepted signal inrelation to a delivered signal and used, in conjunction with a model,such as the above dielectric thorax model, to calculate individualthoracic parameters.

Reference is now made to a model that is defined for narrowband signalspassing through the lungs of the subject. This model may be adjusted forother analyses of other signals, for example EM signals which aretransmitted and captured from a to probe that is attached on the back,the chest, and/or below the arm of the subject. In such embodiments, themodel may be defined as follows:

$\begin{matrix}{{Amp} = {{\overset{\_}{E_{ratio}}} = ^{{- j}\; 2\pi \frac{f}{C}\Sigma_{i \in \; {tissues}}{D_{i} \cdot {{Im}{(\sqrt{ɛ_{i} + {j \cdot ɛ_{i}^{\prime}}})}}}}}} & {{Equation}\mspace{14mu} 16}\end{matrix}$

where Amp=| E_(ratio) | denotes a measured amplitude ratio between atransmitted signal and a received signal representing an electricalcomponent of the electromagnetic signal.

The following equation,

$\begin{matrix}{{\ln ({Amp})} = {{{lm}\; \left( {Amp}_{0} \right)} - {j\; 2\; \pi {\frac{f}{C} \cdot D_{lung} \cdot {{Im}\left( \sqrt{ɛ_{lung} + {j \cdot ɛ_{lung}^{\prime}}} \right)}}}}} & {{Equation}\mspace{14mu} 17}\end{matrix}$

using the notation ∈^(c)=∈+j˜∈′, may use a model, such as the one inEquation 5, for example

$ɛ_{lung}^{C} = \frac{V_{air} + {V_{fluid} \cdot ɛ_{fluid}^{c}}}{V}$

and similarly to the above description approximate

$ɛ_{lung}^{C} \approx {\frac{V_{air} + {V_{fluid} \cdot ɛ_{fluid}^{c}}}{V}.}$

Using a natural logarithm, the following is received:

$\begin{matrix}{{\ln ({Amp})} = {{\ln \; \left( {Amp}_{0} \right)} - {j\; 2\pi {\frac{f}{C} \cdot D_{lung} \cdot {{Im}\left( \sqrt{\frac{V_{air} + {V_{fluid} \cdot ɛ_{fluid}^{c}}}{V}} \right)}}}}} & {{Equation}\mspace{14mu} 18}\end{matrix}$

whereas mentioned in other described embodiments, controlled and/ormeasured changes in air content (Δv_(i)) enable extraction of otherindividual thoracic parameters. For example, as described above, ifseveral measurements are taken with known quantities of inhaled air(Δv_(i)) with respect to, the deflated (i.e. post exhalation) state ofthe lung, the following is received:

$\begin{matrix}{{\ln ({Amp})}_{i} = {{\ln \left( {Amp}_{0} \right)} - {j\; 2\pi {\frac{f}{C} \cdot D_{lung} \cdot {{Im}\left( \sqrt{\frac{V_{defiated} + {\Delta \; v_{i}} + {V_{fluid} \cdot ɛ_{fluid}^{c}}}{V_{defiated} + {\Delta \; v_{i}} + V_{fluid}}} \right)}}}}} & {{Equation}\mspace{14mu} 19}\end{matrix}$

Using the known values of four or more inhaled quantities (ΔV_(i)) andtheir corresponding phase measurements ln(Amp)_(i) one may solve andobtain the following parameters ln (Amp₀), V_(deflated), V_(fluid), andD_(lung).

In these embodiments, extracted V_(deflated) and V_(fluid) are two ofthe individual thoracic parameters of interest.

According to some embodiments of the present invention, the above modelsshare parameters to create a hybrid model that can enhance the accuracyof the results of the estimation of the individual thoracic parameters.Combinations of the models may be implemented as extended sets ofequations solved in any of the mentioned methods or others known in theart. In a similar manner, any of the aforementioned models may becombined with one another and/or with other models.

According to some embodiments of the present invention, multiplefrequencies may be used by a thoracic monitoring device and/or thoracicanalysis device. The above and other possible models may be used with avaried frequency content to obtain an accurate estimation of theparameters in view of measurement errors.

For example, ∈^(c) _(fluid) given in the above models and assuming agiven frequency, has different values at different frequencies.Performing measurements at multiple frequencies creates a plurality oflinearly independent sets of equations, allowing more accurateestimations of the individual thoracic parameters. Multiple frequenciesmeasurements may be measured substantially simultaneously to createadditional equations with the same air content status of the lung at thesame point in time.

Similar thorax models to the ones above may be used with multiplefrequencies based thorax analysis devices for modeling effects ofindividual thoracic parameters and obtaining clinical parameters.Additionally in a similar manner similar methods for deriving individualthoracic parameters using multiple frequencies can be employed.

Optionally, measurements at multiple frequencies are used to overcomeone or more phase ambiguity problems, for example 2*P_(i) uncertainty inthe measured phase in the presence of measurement noise that may arisewhen analyzing a phase of a low bandwidth signal. For example, it ispossible to estimate a phase group delay of a wideband modulated signalin order to resolve phase ambiguities, and then extract the frequencyspecific phase shifts to be used in one or more of the above models. Forexample Equation 19 may be used with simultaneous measurements ofmultiple frequencies f_(j) to produce the following set of equations:

$\begin{matrix}{{\ln ({Amp})}_{i,j} = {{\ln \left( {Amp}_{0} \right)} - {j\; 2\pi {\frac{f}{C} \cdot D_{lung} \cdot {{Im}\left( \sqrt{\frac{V_{defiated} + {\Delta \; v_{i}} + {V_{fluid} \cdot {ɛ^{c}\left( f_{j} \right)}_{fluid}}}{V_{defiated} + {\Delta \; v_{i}} + V_{fluid}}} \right)}}}}} & {{Equation}\mspace{14mu} 20}\end{matrix}$

According to some embodiments of the present invention, EM signals frommultiple transducers which are placed in multiple locations (e.g.multiple locations on the subject's thorax) to monitor the subject areseparately analyzed. Optionally, two signal transducers are placed intwo different locations used to transmit EM signals between them.However, one or more of them may transmit a signal and measure it'sreflection in addition or instead. When more than two transducers areused additional paths may be employed. This may allow, for example,reducing measurement errors. Multiple locations may allow receiving EMsignals passing via multiple paths.

Assuming that the paths are in the same general region, fluid content ineach path may be assumed to be the same. Thus, for each such path, adifferent equation may be solved to calculate the individual thoracicparameters of interest. For example, in any of the above models eachpath is associated with a different D_(lung) parameter. Simultaneousmeasurements may be used in a single equation system, with more linearlyindependent equations, that may be used for more robust estimationsunder certain measurement noise conditions.

As an example, Equation 6 is used with controlled changes in lung aircontent and simultaneous 2-path measurements to produce the following:

$\begin{matrix}{{\phi_{i,j} \cong {\overset{\sim}{\phi} + {150 \cdot D_{{lung}_{j}} \cdot \sqrt{\frac{V_{fluid}}{V_{deflated} + {\Delta \; {Vi}}}}}}},{j = 1},2} & {{Equation}\mspace{14mu} 21}\end{matrix}$

Optionally, in this example, less than three measurements are used, forexample when parameters are from different sources, for instance whenthe volume of the lungs is received from an external device and/orinputted by the subject and/or any operator.

Optionally, multiple locations and multiple frequencies may be combinedto create one or more equation systems that increase robustness of theestimation of the individual thoracic parameters.

For example, reference is now made to FIG. 8, which is an experimentgraph reflecting a calculation of lung fluid concentration 311calculated based on EM measurement of an animal subject compared to a CTbased estimation 312 of the same parameter based on multiple imagesacquired along the course of the experiment. The experiment is heldconcurrently with breathing volume spirometer measurements, and usingthe above mentioned model describing signal phase and signal amplitude,with a linear mixture model and a mechanical measurement basedestimation of D. The graph depicts the fluid concentration, alsoreferred to as fluid content, parameter estimation done multiple timesover the course of four hours while the animal lung fluid has changedrapidly using a systemic saline overload experiment protocol.

It should be noted that when the EM signal is a reflected signal, forexample when a single transceiver is used or when a receiving elementand a transmitting element are mounted on the same side of the subjectbody (referred to herein as an S₁₁ probe), a model that takes intoaccount the back and forth route of the EM wave may be employed. Forexample, when a wave is reflected between two layers of dielectricmedia, the coefficient of reflection is as follows:

$\begin{matrix}{R = {\frac{E_{R}}{E_{T}} = \frac{\sqrt{ɛ_{1}} - \sqrt{ɛ_{2}}}{\sqrt{ɛ_{1}} + \sqrt{ɛ_{2}}}}} & {{Equation}\mspace{14mu} 22}\end{matrix}$

where ∈₁ denotes a dielectric coefficient of the first layer and ∈₂denotes a dielectric coefficient of the second layer.

Thus, the S₁₁ coefficient is written as below:

$\begin{matrix}{{S_{11}(V)} = {R_{0} + {C\left( \frac{\sqrt{ɛ_{1}} - \sqrt{ɛ_{lung}(V)}}{\sqrt{ɛ_{1}} + \sqrt{ɛ_{lung}(V)}} \right)}}} & {{Equation}\mspace{14mu} 23}\end{matrix}$

where ∈₁ denotes a dielectric coefficient of the lung wall, ∈_(lung)denotes a dielectric coefficient of the lung tissue, V denotes a lungvolume, and R₀, C denotes constants related to other tissue layers whichare more proximate to the probe and the properties of the probe. Usingthe model, for example such as the one described in Equation 8, thefollowing may be written:

$\begin{matrix}{\sqrt{ɛ_{lung}\left( {\Delta \; V} \right)} = \frac{{\sqrt{ɛ_{air}}\left( {V_{deflated} - V_{fluid} + {\Delta \; V}} \right)} + {\sqrt{ɛ_{fluid}}V_{fluid}}}{V_{deflated} + {\Delta \; V}}} & {{Equation}\mspace{14mu} 24}\end{matrix}$

where V_(deflated) denotes a total lung volume at rest (FRV), then

$\begin{matrix}{\sqrt{ɛ_{lung}(0)} = \frac{{\sqrt{ɛ_{air}}V_{air}} + {\sqrt{ɛ_{fluid}}V_{fluid}}}{V_{deflated}}} & {{Equation}\mspace{14mu} 25}\end{matrix}$

The difference between the signals may be estimated to eliminate R₀:

$\begin{matrix}{{{S_{11}\left( {\Delta \; V_{11}} \right)} - {S_{11}(0)}} = {\frac{\sqrt{ɛ_{1}} - \sqrt{ɛ_{lung}\left( {\Delta \; V_{1}} \right)}}{\sqrt{ɛ_{1}} + \sqrt{ɛ_{lung}\left( {\Delta \; V_{1}} \right)}} - \frac{\sqrt{ɛ_{1}} - \sqrt{ɛ_{lung}(0)}}{\sqrt{ɛ_{1}} + \sqrt{ɛ_{lung}(0)}}}} & {{Equation}\mspace{14mu} 26}\end{matrix}$

Furthermore, the quotient of the signals may be evaluated to eliminateC:

$\begin{matrix}{\frac{{S_{11}\left( {\Delta \; V_{1}} \right)} - {S_{11}(0)}}{{S_{11}\left( {\Delta \; V_{2}} \right)} - {S_{11}(0)}} = \frac{\frac{\sqrt{ɛ_{1}} - \sqrt{ɛ_{lung}\left( {\Delta \; V_{1}} \right)}}{\sqrt{ɛ_{1}} + \sqrt{ɛ_{lung}\left( {\Delta \; V_{1}} \right)}} - \frac{\sqrt{ɛ_{1}} - \sqrt{ɛ_{lung}(0)}}{\sqrt{ɛ_{1}} + \sqrt{ɛ_{lung}(0)}}}{\frac{\sqrt{ɛ_{1}} - \sqrt{ɛ_{lung}\left( {\Delta \; V_{2}} \right)}}{\sqrt{ɛ_{1}} + \sqrt{ɛ_{lung}\left( {\Delta \; V_{2}} \right)}} - \frac{\sqrt{ɛ_{1}} - \sqrt{ɛ_{lung}(0)}}{\sqrt{ɛ_{1}} + \sqrt{ɛ_{lung}(0)}}}} & {{Equation}\mspace{14mu} 27}\end{matrix}$

The above is dependent only on V_(fluid),V_(deflated), ∈₁, ∈_(air),∈_(fluid). V_(deflated), ∈₁ may be deduced from other means ofmeasurements and ∈_(air), ∈_(fluid) are known constants.

Thus, the above equation may be used to find V_(fluid), for exampleusing a numeric scheme.

It is expected that during the life of a patent maturing from thisapplication many relevant methods and systems will be developed and thescope of the term a probe, a to transducer, and an antenna is intendedto include all such new technologies a priori.

As used herein the term “about” refers to ±10%.

The terms “comprises”, “comprising”, “includes”, “including”, “having”and their conjugates mean “including but not limited to”. This termencompasses the terms “consisting of” and “consisting essentially of”.

The phrase “consisting essentially of” means that the composition ormethod may include additional ingredients and/or steps, but only if theadditional ingredients and/or steps do not materially alter the basicand novel characteristics of the claimed composition or method.

As used herein, the singular form “a”, “an” and “the” include pluralreferences unless the context clearly dictates otherwise. For example,the term “a compound” or “at least one compound” may include a pluralityof compounds, including mixtures thereof.

The word “exemplary” is used herein to mean “serving as an example,instance or illustration”. Any embodiment described as “exemplary” isnot necessarily to be construed as preferred or advantageous over otherembodiments and/or to exclude the incorporation of features from otherembodiments.

The word “optionally” is used herein to mean “is provided in someembodiments and not provided in other embodiments”. Any particularembodiment of the invention may include a plurality of “optional”features unless such features conflict.

Throughout this application, various embodiments of this invention maybe presented in a range format. It should be understood that thedescription in range format is merely for convenience and brevity andshould not be construed as an inflexible limitation on the scope of theinvention. Accordingly, the description of a range should be consideredto have specifically disclosed all the possible subranges as well asindividual numerical values within that range. For example, descriptionof a range such as from 1 to 6 should be considered to have specificallydisclosed subranges such as to from 1 to 3, from 1 to 4, from 1 to 5,from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individualnumbers within that range, for example, 1, 2, 3, 4, 5, and 6. Thisapplies regardless of the breadth of the range.

Whenever a numerical range is indicated herein, it is meant to includeany cited numeral (fractional or integral) within the indicated range.The phrases “ranging/ranges between” a first indicate number and asecond indicate number and “ranging/ranges from” a first indicate number“to” a second indicate number are used herein interchangeably and aremeant to include the first and second indicated numbers and all thefractional and integral numerals therebetween.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination or as suitable in any other describedembodiment of the invention. Certain features described in the contextof various embodiments are not to be considered essential features ofthose embodiments, unless the embodiment is inoperative without thoseelements.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims.

All publications, patents and patent applications mentioned in thisspecification are herein incorporated in their entirety by referenceinto the specification, to the same extent as if each individualpublication, patent or patent application was specifically andindividually indicated to be incorporated herein by reference. Inaddition, citation or identification of any reference in thisapplication shall not be construed as an admission that such referenceis available as prior art to the present invention. To the extent thatsection headings are used, they should not be construed as necessarilylimiting.

1. A device of deriving one or more individual thoracic parameters of asubject, comprising: a processor; a first interface for receiving aplurality of measurements of EM signal beams from a thoracic intrabodyarea of lungs of a subject, wherein each of said plurality ofmeasurements of EM signal beams reflects a different time point during athoracic volume manipulation of said subject; a second interface forreceiving a plurality of thoracic volume values, wherein each of saidplurality of thoracic volume values reflects a different time pointduring a thoracic volume manipulation of said subject; and an individualthoracic parameter module which uses said processor to calculate atleast one individual thoracic parameter using said plurality of EMmeasurements and said plurality of thoracic volume values.
 2. The deviceof claim 1, wherein said first interface is associated with a probehaving at least one antenna for capturing a plurality of later EMmeasurements from a subject and a thoracic analysis unit module whichmonitors thoracic fluid by an analysis of said plurality of later EMmeasurements in combination with said at least one individual thoracicparameter.
 3. The device of claim 1, wherein said second interface isassociated with an instrument for measuring at least one of a breathingairflow of said subject for receiving said plurality of thoracic volumevalues.
 4. (canceled)
 5. The device of claim 1, wherein said processoris associated with a presentation unit which presents instructionsindicative of how to perform said thoracic volume manipulation in acorrelated manner with the measurement of said plurality of thoracicvolume values.
 6. (canceled)
 7. The device of claim 1, comprising aprocessing unit configured to derive one or more clinical parametersaccording to the at least one individual thoracic parameter and datarelating to electromagnetic (EM) radiation received from an internaltissue of the subject.
 8. A method of deriving one or more individualthoracic parameters of a subject, comprising: receiving a plurality ofEM measurements of a plurality of EM signal beams from a thoracicintrabody area of lungs of a subject performing at least one thoracicvolume manipulation; deriving a plurality of thoracic volume valuescorresponding to a plurality of said plurality of EM measurements; andderiving at least one individual thoracic parameter of said subjectusing said plurality of EM measurements and said plurality of thoracicvolume values.
 9. (canceled)
 10. The method of claim 8, wherein saidplurality of thoracic volume values comprise at least breathing value ofsaid subject.
 11. The method of claim 8, wherein said plurality of EMmeasurements are received from a thoracic monitoring device monitoringsaid lungs; and the method comprises calibrating a thoracic analysisdevice using at least one of said at least one individual thoracicparameter.
 12. The method of claim 8, wherein information relating tosaid at least one individual thoracic parameter is stored during acalibration session of a thoracic analysis device and is used foranalyzing a plurality of later EM measurements which are measured duringa monitoring session of said thoracic monitoring device.
 13. The methodof claim 11, where calibrating comprises updating a dielectric model ofa thorax according to said individual thoracic parameters. 14.(canceled)
 15. The method of claim 8, wherein said at least oneindividual thoracic parameter comprises a member of a group consistingof: heart dimension(s), heart position, fat layer dimensions, thoracicmuscle dimension(s), thoracic rib dimension(s), thoracic rib position,lung volume, lung dimension(s), and thorax dimension(s).
 16. The methodof claim 8, wherein said at least one individual thoracic parametercomprises dielectric related properties of at least one of a thoracictissue and a thoracic organ of said subject.
 17. The method of claim 8,wherein said at least one individual thoracic parameter is used incombination with at least one EM measurement to derive at least oneclinical parameter of said subject.
 18. The method of claim 8, whereinsaid plurality of EM signals pass through said lungs. 19-22. (canceled)23. The method of claim 8, further comprising presenting to said subjectbreathing instructions for said subject to perform during said thoracicvolume manipulation.
 24. (canceled)
 25. The method of claim 8, whereinsaid deriving at least one individual thoracic parameter is performedaccording to one or more demographic parameters relating to the subject.26-27. (canceled)
 28. The method of claim 8, wherein said deriving atleast one individual thoracic parameter is performed according to ameasured amplitude ratio between a transmitted signal and a receivedsignal. 29-30. (canceled)
 31. The method of claim 17, wherein said atleast one clinical parameter comprises a member of a group consisting offluid and/or gas volume in the thorax and/or lung tissue, percentage offluid in a lung tissue, parameters indicative of fluid content and/orcontent change, and/or percentage of fluid change in lung tissue. 32.The method of claim 8, wherein said deriving at least one individualthoracic parameter comprises calculating a phase shift based on saidplurality of EM measurements.
 33. The method of claim 8, wherein saidderiving at least one individual thoracic parameter comprisescalculating fluid content of said lungs.
 34. The method of claim 8,wherein said deriving at least one individual thoracic parametercomprises calculating a depth of said lungs. 35-43. (canceled)